Washington, May 8 (IANS): Sleep-deprived people are more prone to taking disastrous decisions that often make a difference between life and death in real life crisis situations such as in the operating room, on the battlefield or during a police shootout, says a new study.

The findings suggest that going without sleep for long periods can lead doctors, first responders, military personnel and others in a crisis situation to make catastrophic decisions.

"Our findings tell us that putting sleep-deprived people in perilous environments is an inherently risky business and raises a number of medical, legal and financial implications," said Hans Van Dongen, director of Sleep and Performance Research Centre at the Washington State University Spokane.

Investigations into the Chernobyl nuclear power plant meltdown in Ukraine, the grounding of the Exxon Valdez oil tanker and the explosion of the space shuttle Challenger all concluded that sleep-deprived operators played a role in causing the accidents.

The researchers recruited 26 healthy adults to take part in their study conducted at the Spokane sleep center.

Thirteen of the participants were randomly selected to go 62 hours without sleep two days into the study while the other half of the group was allowed to rest.

For six days and nights, the participants lived in a hotel-like laboratory where they performed a specially designed reversal learning task to test their ability to use feedback to guide future decisions.

In the task, the participants were shown a series of numbers that, unknown to them, were pre-assigned to have either a "go" (response) or "no go" (non-response) value.

They had less than a second to decide whether or not to respond to each number shown.

Every time they correctly identified a number with a "go" value, they received a fictitious monetary reward. Errors resulted in a loss.

After a while, both the sleep-deprived group and the controls started to catch on and selected the right numbers.

Then the tricky part came. The researchers reversed the contingencies so that participants had to withhold a response to the "go" numbers and respond to the "no go" numbers.

The switch confounded the sleep-deprived participants. Even after being shown 40 numbers with reversed contingencies, they had almost zero success. On the other hand, the rested participants would catch on to the switch within eight-16 numbers.

The study appeared in the journal Sleep.